U.S. patent application number 12/614035 was filed with the patent office on 2011-05-12 for micro-turbine combustor.
This patent application is currently assigned to JETHEAT INC.. Invention is credited to Nancy Ann Gordon, Richard W. Gordon.
Application Number | 20110107763 12/614035 |
Document ID | / |
Family ID | 43970740 |
Filed Date | 2011-05-12 |
United States Patent
Application |
20110107763 |
Kind Code |
A1 |
Gordon; Richard W. ; et
al. |
May 12, 2011 |
MICRO-TURBINE COMBUSTOR
Abstract
A micro gas turbine engine for use in a turbo heater or
co-generation application is described. The micro gas turbine
engine includes a fuel delivery system which minimizes the
development of deposits in the air-fuel passageway. To this end, a
fuel delivery channel formed between a fuel deflector and a slinger
body is formed with a contoured or undulating surface. A fuel
deflector ring is interposed between the fuel delivery channel and
the slinger impeller to facilitate the flow of the air-fuel mixture
into the combustion chamber.
Inventors: |
Gordon; Richard W.; (Ray,
MI) ; Gordon; Nancy Ann; (Ray, MI) |
Assignee: |
JETHEAT INC.
Fraser
MI
|
Family ID: |
43970740 |
Appl. No.: |
12/614035 |
Filed: |
November 6, 2009 |
Current U.S.
Class: |
60/737 ;
60/690 |
Current CPC
Class: |
F02C 7/22 20130101; Y02E
20/14 20130101; F23C 2900/03001 20130101; F02C 3/14 20130101; F05D
2250/82 20130101 |
Class at
Publication: |
60/737 ;
60/690 |
International
Class: |
F02C 7/22 20060101
F02C007/22; F01K 9/00 20060101 F01K009/00 |
Claims
1. A gas turbine engine comprising: an engine housing rotatably
supporting a shaft assembly on a bearing assembly; a combustion
chamber encased with said engine housing; a compressor coupled to
said shaft assembly for rotation about a longitudinal axis, said
compressor in fluid communication with said combustion chamber; a
turbine coupled to said shaft assembly for rotation about said
longitudinal axis, said turbine in fluid communication with said
combustion chamber; and a fuel delivery system for delivering an
air-fuel mixture to said combustion chamber, said fuel delivery
system including: a fuel slinger assembly rotatably supported on
said shaft assembly including a slinger body and a slinger
impeller, said slinger impeller having a discharge passage in fluid
communication with said combustion chamber; and a fuel deflector
fixedly supported within said engine housing, said fuel deflector
having a inner surface spaced apart from and facing an outer
surface of said slinger body to form a fuel delivery channel, said
fuel delivery channel beginning at an inlet in fluid communication
with a fuel feed tube, diverging along said longitudinal axis and
terminating at an outlet adjacent said discharge passage of said
slinger impeller, and wherein at least one of said inner and outer
surfaces having a contoured surface formed therein,.
2. The gas turbine engine of claim 1 wherein said contoured surface
comprises a plurality of concentric undulations formed in said
inner surface along said longitudinal axis from said inlet and said
outlet.
3. The gas turbine engine of claim 2 wherein said contoured surface
further comprises a radiused transition between each of said
plurality of concentric undulations.
4. The gas turbine engine of claim 1 wherein said slinger impeller
is secured to said slinger body for co-rotation therewith.
5. The gas turbine engine of claim 1 further comprising a plurality
of holes extending generally radially through said slinger impeller
to form said discharge passage.
6. The gas turbine engine of claim 5 wherein each of said plurality
of holes diverges from an inlet port adjacent said fuel delivery
channel to an outlet port adjacent said combustion chamber to
define a tapered discharge passage.
7. The gas turbine engine of claim 5 wherein each of said plurality
of holes has an inlet port adjacent said fuel delivery channel and
an outlet port adjacent said combustion chamber, said outlet port
being circumferentially offset from a radial line extending through
the inlet port to define a back-swept passage.
8. The gas turbine engine of claim 5 wherein each of said plurality
of holes has an contoured inlet port adjacent said fuel delivery
channel and an outlet port adjacent said combustion chamber.
9. The gas turbine engine of claim 1 further comprising a fuel
deflector ring having an angled face interposed between said outlet
of said fuel delivery channel and said discharge passage.
10. The gas turbine engine of claim 9 wherein said fuel deflector
ring is secured to said slinger body for co-rotation therewith.
11. The gas turbine engine of claim 9 wherein said fuel deflector
ring further comprises a plurality of blades extending from said
angled face and equidistantly spaced around said deflector
ring.
12. The gas turbine engine of claim 1 in combination with a heat
exchange element in fluid communication with said turbine such that
exhaust gases discharged from the gas turbine engine pass through
said heat exchange element.
13. The gas turbine engine of claim 1 in combination with a
catalytic converter element in fluid communication with said
turbine such that exhaust gases discharged from the gas turbine
engine pass through said catalytic converter element.
14. A gas turbine engine comprising: a turbine nozzle assembly
disposed within an engine housing and supporting a nozzle hub; a
shaft assembly disposed within said nozzle hub and defining an
annulus therebetween; a bearing assembly disposed within said
annulus and supporting said shaft assembly in said nozzle hub for
rotation about a longitudinal axis; a fuel deflector supported on
said nozzle hub and extending from said annulus, said fuel
deflector having a contoured inner surface; a turbine operably
disposed on a first end of said shaft assembly; a compressor
operably disposed on a second end of said shaft assembly; a
combustion chamber concentrically disposed about the shaft assembly
between the compressor and the turbine; a fuel feed tube for
delivering fuel to said annulus; a fuel slinger assembly coupled to
said shaft assembly for rotation therewith, said fuel slinger
assembly including a slinger body with an outer surface spaced
apart from and facing said inner surface of said fuel deflector to
form a fuel delivery channel, said fuel delivery channel beginning
at an inlet in fluid communication with said annulus, diverging
along said longitudinal axis and terminating at an outlet, and a
slinger impeller having a discharge passageway formed therein
adjacent said outlet to provide fluid communication from said fuel
delivery channel to said combustion chamber.
15. The gas turbine engine of claim 14 wherein said contoured
surface comprises a plurality of concentric undulations formed in
said inner surface along said longitudinal axis from said inlet and
said outlet.
16. The gas turbine engine of claim 15 wherein said contoured
surface further comprises a radiused transition between each of
said plurality of concentric undulations.
17. The gas turbine engine of claim 14 further a plurality of holes
extending through said slinger impeller to form said discharge
passage, each of said plurality of holes diverges from an inlet
port adjacent said fuel delivery channel to an outlet port adjacent
said combustion chamber to define a tapered discharge passage.
18. The gas turbine engine of claim 17 wherein said outlet port is
circumferentially offset from a radial line extending through said
inlet port to define a back-swept passage.
19. The gas turbine engine of claim 14 further comprising a fuel
deflector ring secured to said slinger body for co-rotation
therewith, said deflector ring having an angled face interposed
between said outlet of said fuel delivery channel and said
discharge passage.
20. The gas turbine engine of claim 19 wherein said fuel deflector
ring further comprises a plurality of blades extending from said
angled face and equidistantly spaced around said deflector
ring.
21. The gas turbine engine of claim 14 in combination with a heat
exchange element in fluid communication with said turbine such that
exhaust gases discharged from the gas turbine engine pass through
said heat exchange element.
22. The gas turbine engine of claim 14 in combination with a
catalytic converter element in fluid communication with said
turbine such that exhaust gases discharged from the gas turbine
engine pass through said catalytic converter element.
Description
FIELD
[0001] The present disclosure relates to a self-sustaining
co-generator which utilizes a micro gas turbine engine to provide
heated air through a heat exchanger, catalyst or direct fire and
for generating rotary drive which can power an auxiliary generator,
and more particularly to an improved fuel deflector/slinger
assembly for the micro gas turbine engine which minimizes particle
build-up in the fuel delivery system.
BACKGROUND
[0002] This section provides background information related to the
present disclosure which is not necessarily prior art.
[0003] Recent efforts have shown that micro gas turbine engines can
be useful in co-generation applications to provide heat and
auxiliary electrical power. In particular, the small gas turbine
has proven to be light, relatively trouble free and extremely
efficient such that it makes an excellent heater. Exemplary
embodiments of a co-generator utilizing a micro gas turbine engine
are the subject of U.S. Pat. No. 6,073,857, U.S. Pat. No. 6,161,768
and U.S. Pat. No. 6,679,433 by Gordon et al.
[0004] These embodiments disclosed by Gordon et al. featured fuel
entering the rear housing via a fuel delivery tube; where a minor
amount of heat is added. The fuel delivered in the rear housing
through drilled holes enters a delivery space between two
Belleville springs. Hot air is also introduced at this site, and
the fuel-air mixture is fed into the bearing, cooling and
lubricating the bearing. Some fuel flows around the bearing
flooding the spring suspension system, all the while picking up
heat. The mixture then enters a slinger plenum chamber defined by a
rotating slinger body and a stationary fuel deflector tube.
Additional hot air from the combustion chamber is added before the
fuel-air mixture enters the slinger impeller which adds more heat
and injects it into the combustion chamber.
[0005] With this configuration, fuel delivery is adequate and a
blue flame or non-visible flame is produced in the combustion
chamber with moderately cold ambient temperatures such as those
experienced in the northern states of the continental United
States. However, extremely cold ambient temperatures such as those
experienced in Canada and Alaska changes the stoichiometry of
combustion which presents complication factors. It was known that a
fuel heater may be employed to thermally condition the fuel and it
was known to insulate the annulus between the combustor and the
engine housing to maintain a more consistent operating temperature
in the combustion chamber.
[0006] During prolonged operation in extreme conditions, it has
been observed that carbon deposits can form in the fuel deflector,
slinger body and slinger assembly and could not be eliminated.
Conventional solutions to this problem were ineffective for
eliminating these deposits, eventually leading to blockages in the
fuel delivery system. Accordingly, there is a need in the art to
provide a fuel delivery system in a mirco gas turbine engine that
provides adequate fuel flow and thermal condition without
developing excessive carbon deposits resulting in fuel blockage
build-up.
SUMMARY
[0007] This section provides a general summary of the disclosure,
but is not a comprehensive disclosure of its full scope or all of
its features.
[0008] An improved micro gas turbine engine, and in particular an
improved fuel deflector/slinger assembly are the subject of this
patent disclosure. As described above, the mixture entering the
fuel deflector, includes air, liquid fuel, and vaporized fuel
extending into possibly a fuel plasma which essentially constitutes
a complete range of heated partially combusted fuel. In order to
minimize particle buildup within the fuel delivery system, the
inner surface of the fuel deflector is contoured with an undulation
that reduces deposits to near zero. The specific dimensions of the
surface contouring is a function of the fuel preparation for which
the fuel temperature, velocity and the amount of mechanical mixing
which would be similar regardless of the heaters size, and thus is
readily scalable to a gas turbine engines having a range of
displacement.
[0009] An improved slinger impeller is also the subject of this
patent disclosure. In particular, the improved slinger impeller
features completely round channels eliminating corners and pockets
where deposits can readily form. The channels are formed by
drilling tapered holes around the impeller diameter. The improved
impeller also features less back sweep than previous impellers.
[0010] In addition, a radial deflector ring having multiple short
triangular blades is positioned upstream of the impeller. The
deflector ring facilitates flow from the channel bounded by the
fuel deflector tube into the inducer and then into the impeller.
The deflector ring also mixes and impacts the fuel, air, and
combustion products mixture to a final near uniform product,
further reducing the tendency for deposits formation.
[0011] Further scope of applicability of the present invention will
become apparent from the detailed description provided hereinafter.
It should be understood however that the detailed description and
specific examples, while indicating preferred embodiments of the
invention, are intended for purposes of illustration only, since
various changes and modifications within the spirit and scope of
the invention will become apparent to those skilled in the art from
this
DETAILED DESCRIPTION
[0012] Further areas of applicability will become apparent from the
description provided herein. The description and specific examples
in this summary are intended for purposes of illustration only and
are not intended to limit the scope of the present disclosure.
DRAWINGS
[0013] The drawings described herein are for illustrative purposes
only of selected embodiments and not all possible implementations,
and are not intended to limit the scope of the present
disclosure.
[0014] FIG. 1 is a partial cross-sectional view of a turbo heater
having a micro gas turbine engine and a catalytic heat exchange
element;
[0015] FIG. 2A is a detailed view illustrating the nozzle hub, rear
bearing assembly and fuel slinger of the gas turbine engine
illustrated in FIG. 1;
[0016] FIG. 2B is an enlarged view of the fuel delivery system and
the rear bearing assembly indicated at B-B in FIG. 2A;
[0017] FIG. 3A is a detailed illustration of the fuel deflector
shown in FIG. 2;
[0018] FIG. 3B is an enlarged view of the undulating surface formed
on the inner surface of the fuel deflector indicated at B-B in FIG.
3A;
[0019] FIG. 3C is an enlarged view of the flange on the fuel
deflector that interfaces with the rear bearing race indicated at
C-C in FIG. 3A;
[0020] FIG. 4A is a detailed illustration of the slinger assembly
shown in FIG. 2;
[0021] FIG. 4B is an enlarged view of the deflector ring;
[0022] FIG. 4C is a detailed illustration of the slinger inlet port
taken at line C-C shown in FIG. 4A; and
[0023] FIG. 4D is a cross-sectional view taken at line D-D.
[0024] Corresponding reference numerals indicate corresponding
parts throughout the several views of the drawings.
DETAILED DESCRIPTION
[0025] Example embodiments will now be described more fully with
reference to the accompanying drawings. These example embodiments
are provided so that this disclosure will be thorough, and will
fully convey the scope to those who are skilled in the art. Various
specific details are set forth such as examples of components,
devices, and methods, to provide a thorough understanding of
embodiments of the present disclosure. It will be apparent to those
skilled in the art that specific details need not be employed, that
example embodiments may be embodied in different forms and that
neither should be construed to limit the scope of the disclosure.
In some example embodiments, well-known processes, well-known
device structures, and well-known technologies are not described in
detail.
[0026] With reference now to FIGS. 1 and 2, a co-generator or turbo
heater 10 includes a gas turbine engine 12 and a catalytic heat
exchange element 14 which are supported within a frame assembly 16.
Gas turbine engine 12 draws ambient air through a compressor 18,
receives fuel from a fuel system to form an air-fuel mixture,
combusts the air-fuel mixture in a combustor 20 and discharges and
expands the exhaust gases through a turbine 22. As such, gas
turbine engine 12 provides a source of heat, as well as a source of
rotary power. The rotating components of gas turbine engine 12,
namely compressor 18 and turbine 22, are mounted on a common
high-speed shaft assembly 24. The shaft assembly 24 is coupled
through a reduction gear assembly or gear box to an axial fan 26
and a starter motor 28. The gear box may also be coupled to a
generator set 30 (not shown) for providing electrical power. The
starter motor 28 is coupled to the axial fan 26 through a one-way
over-running clutch assembly which permits power transmission in a
first rotational direction and free wheeling in a second rotational
direction.
[0027] Turbo heater 10 is a diesel fueled self-contained and
self-sustaining heating system for supplying heated air and
electrical power in remote locations. Gas turbine engine 12 is
designed to supply the majority of its energy as heat in the form
of exhaust gases, and a minor amount as shaft power used to drive
the axial fan 26 and other auxiliary power generation
mechanisms.
[0028] Turbo heater 10 is designed to feature economical
construction and is especially designed for reduced manufacturing
cost. The internal aerodynamics, such as the turbine and compressor
wheels, use well-developed turbocharger technology. For example,
the preferred flow and pressure ratios are nearly optimum for
automotive turbocharger components, and are thus near-optimum for
use in the turbo heater 10. A peak cycle temperature of
1500.degree. Fahrenheit (.degree. F.) is preferred to allow the use
of economical materials for the high temperature components.
[0029] With continued reference to FIG. 1, a heat exchange element
14 is used to recover the resulting heat in the exhaust gases. In
this regard, turbo heater 10 is equipped with a suitable catalytic
converter 34 which reduces the carbon monoxide and other toxic
emissions in the exhaust gases to supply essentially breathable
heated air as illustrated in FIG. 1. This exemplary embodiment is
especially suitable for outdoor construction applications, wherein
heated air is produced using a catalytic element 34 located within
the heat exchanger assembly 14. Since the combustor 20 in the gas
turbine engine 12 produces significantly less carbon monoxide (CO)
as compared to a gasoline spark ignition engine, a properly fitted
catalytic element 34 on the gas turbine engine 12 can reduce the
emissions to acceptable levels. The catalytic element 34 is fitted
directly to the exhaust of gas turbine engine 12 by means of a
diffuser duct 36. The exhaust from the catalytic element 34 will be
in the range of 1250.degree. F. to 1300.degree. F. maximum and the
additional air flow from the axial fan 26 will pass around the
catalytic element 34 and within the volume defined by housing 38
for mixing and blending with fresh air to produce a relatively even
discharge temperature of approximately 250.degree. F. In this
manner, the efficiency of the turbo heater 10 can approach 97%,
depending upon the amount of electrical power being concurrently
generated.
[0030] Alternately, an air-to-air heat exchangers, an air-to-liquid
heat exchanger, a liquid coil or a combination thereof may be used
to generate heated air, heated liquid or both. Similarly, in some
applications where human consumption of the heated air is not a
requirement, a heat exchanger or catalytic converter may not be
required such that the exhaust gas directly from the gas turbine
engine 12 is mixed with fresh air from the axial fan 26 to produce
a heated mixture of exhaust gases and air.
[0031] The turbo heater 10 is self-contained and nearly
instantaneously starting, and will operate at a minimum heat output
on a reasonable on-off cycle for lower heat requirements. Operation
of the turbo heater 10 in this manner can provide an environment of
uniform heat, using the minimum fuel necessary. As such, the turbo
heater 10 is an ideal source of heated air as it can supply a large
quantity of heat at relatively low ambient temperatures. For
example, while nominally rated at 500,000 Btu/hr, the turbo heater
10 can be modulated from less than 250,000 Btu/hr to greater than
750,000 Btu/hr at an ambient temperature of minus 50.degree. F.
[0032] Further details concerning the components and operation of
the turbo heater 10 and the gas turbine engine 12 are set forth in
U.S. Pat. No. 6,073,857, U.S. Pat. No. 6,161,768 and U.S. Pat. No.
6,679,433 to Gordon et al. The entire disclosure of each of the
above patents is incorporated herein by reference.
[0033] Referring now to FIGS. 2A and 2B, the high speed shaft
assembly 24 includes a center shaft assembly 40 located forward of
the turbine 22 and extending through turbine nozzle assembly 42.
The center shaft assembly 40 includes fuel slinger assembly 46
which is press fit onto a pilot spigot 48 formed as a part of the
compressor 18. High speed shaft assembly 24 is rotatably supported
by rear bearing assembly 50 having inner bearing race 52, outer
bearing race 54, and ball bearing 56. Compression springs 58 in
combination with Belleville springs 60 biases the shaft assembly 24
towards the compressor side of the gas turbine engine 12 to
properly locate the shaft assembly.
[0034] With reference to FIG. 2B, the center shaft assembly 40 also
includes scavenger blower 62 with impeller blades 64 extending from
scavenger vane 66. A fixed diffuser assembly 68 is positioned
between the spring seat 70 and cover plate 72. The fixed diffuser
assembly 68 includes rear diffuser blades 74 adjacent to scavenger
blower 62 and front diffuser blades 76 which abuts cover plate 72.
Air is introduced from the compressor 22 through passageway 76 to
the region between the center shaft assembly 40 and the nozzle
assembly 42. The pressurized air flows through the rear diffuser
assembly 68, over and down through annulus 78 and to annulus 80
between cover plate 72 and rear bearing assembly 50. Fuel is
communicated from the fuel feed tube 78 through a fuel passageway
86 and into annulus 82. Fuel flows between Belleville springs 60
and cover plate 72 into open annulus 84 in the bearing assembly 50
where the fuel is conditioned and mixed with pressurized air from
the compressor 18 such that it is atomized.
[0035] The fuel-air mixtures passes through the rear bearing
assembly 50 and passes into fuel delivery channel 94. The fuel
delivery channel 94 is diverging with respect to the longitudinal
axis of the center shaft assembly 40 and is defined between fuel
slinger assembly 46 and fuel deflector 96. As can be seen in FIGS.
3A and 3C, the rear surface 96b has a recessed formed therein
adjacent to rear bearing assembly 50 to facilitate fuel delivery
into the channel 94. With reference to FIGS. 2A and 4A-4D, the
slinger assembly 46 is a part of the center shaft assembly 40 and
includes slinger body 98, radial deflector ring 100 and slinger
impeller 102. Fuel is centrifugally driven forwardly onto the
radial deflector ring 100 and outwardly through the ports 104
formed in the slinger impeller 102. Specifically, an outer surface
of the slinger body 98 and the inner surface of the fuel deflector
96 define a radially diverging fuel delivery channel 94. The radial
deflector ring 100 is located at the end of the fuel delivery
channel 94 and has an angled face 106 directed toward the inlet
ports 104. A series of triangular blades 108 extend from angled
face 106. As presently preferred, sixteen blades 108 are
equidistantly spread about the deflector ring 100. The angled face
106 and triangular blades 108 efficiently direct the air-fuel
mixture from the fuel delivery channel 94 to the inlet ports 104
formed in the slinger impeller, while further minimizing an
accumulation of deposits in the fuel delivery path.
[0036] As best shown in FIG. 4C, inlet port 104 is radiused to
eliminate any surface normal to the flow of the air-fuel mixture.
The slinger impeller 102 also has smoothly shaped discharge
passages 110 eliminating corner regions where deposits can readily
form which terminate at outlet ports 112. The discharge passages
110 are formed by drilling tapered holes around the circumference
of the slinger impeller 102 eliminating corners in the fuel
delivery path. The slinger impeller 102 is also provided with a
small back sweep to define a back-swept passage as best seen in
FIG. 4D. In particular, the outlet port 112 is circumferentially
offset from a radial line extending through the inlet port as shown
in FIG. 4D.
[0037] As previously mentioned, the mixture entering the fuel
deflector 96, is air, liquid fuel, vaporized fuel extending into
possibly a plasma, essentially a complete range of heated partially
combusted fuel which can result in a slow particle build-up over
time to the point of creating a blockage in the fuel delivery path.
As best shown in FIGS. 3A and 3B, the inner surface 96i of fuel
deflector is provided with an undulating contour to alleviate this
problem. As presently preferred, a series of concentric undulations
are formed in the inner surface 96i of the fuel deflector 96 along
the longitudinal axis. These concentric undulations extend from the
inlet to the outlet of fuel delivery channel 94. In particular,
experiments conducted on a micro gas turbine engine with a fuel
deflector having a twelve-part undulation, each with a pitch (p) of
approximately 1.5 mm, a depth (d) of about 0.1 mm and a leading
edge radius (r) of about 0.8 mm, produced a significant reduction
in deposits approaching zero measurable deposits. The scaling
(i.e., relative size) of the undulating contour for different
displacement engines is only limited to surface dimensions close to
those stated above as the condition of the fuel is a function of
the fuel preparation for which the fuel temperature, velocity and
the amount of mechanical mixing which would be similar regardless
of the heaters size.
[0038] The fuel-air mixture being discharged from the fuel delivery
channel 94 enters the slinger assembly 46, along with additional
air entrained from the combustor 20. The air-fuel mixture is
combusted and exhaust through turbine 22 which in turn drives
compressor 18 via shaft assembly 24.
[0039] One skilled in the art will recognized that the turbo heater
10 may be provided with an engine controller and various sensors to
monitor and control engine operating parameters, an ignition system
for initiating combustion, an electric fuel pump that pumps fuel to
fuel passageway 78, 86 formed in gas turbine engine 12, and a
starting system with a starter motor which is adequately sized to
insure adequate power to start the gas turbine engine 12 during
very cold weather. The details of these components, as well as
operation of the turbo heater 10 are set forth in the patents to
Gordon et al. previously incorporated by reference herein.
[0040] The foregoing description of the embodiments has been
provided for purposes of illustration and description. It is not
intended to be exhaustive or to limit the invention. Individual
elements or features of a particular embodiment are generally not
limited to that particular embodiment, but, where applicable, are
interchangeable and can be used in a selected embodiment, even if
not specifically shown or described. The same may also be varied in
many ways. Such variations are not to be regarded as a departure
from the invention, and all such modifications are intended to be
included within the scope of the invention.
* * * * *